JP6284685B2 - Polymer compositions and extrusion coated articles - Google Patents

Description

  The present invention relates to a polymer composition having improved sealing properties. In particular, the present invention is a polypropylene-based composition blend that makes the polypropylene-based composition blend suitable for producing articles comprising at least two layers and prepared by an extrusion coating process. The present invention relates to a polypropylene-based composition blend having excellent sealability and excellent processability characteristics such as Furthermore, the present invention provides a polypropylene layer composition having a support layer and improved sealability such as excellent heat resistance and hot tack, and also excellent processability characteristics suitable for extrusion coating The invention relates to extrusion-coated articles comprising at least one film layer of a blend and their preparation.

  Laminates and single or multilayer films are packaging materials that often utilize heat-sealable layer (s). Laminates are fibrous supports such as paper, paperboard or kraft paper or woven or non-woven; metal foils such as aluminum foil or plastic films such as stretched polypropylene film, PET film, PA film or cellophane film, metallized film, or Supports such as combinations thereof are often produced by extrusion coating with a heat sealable layer. Such heat-sealable layers of articles allow materials to be sealed to form structures such as bags or other packages and lid materials. In order to facilitate sealing, heat-sealable films are usually used alone or as the outermost or innermost layer in the case of a multilayer structure. As an additional layer, fibrous materials, polymeric materials, metallic materials or any material required to produce the desired structure and properties can be used.

  To prepare an extrusion coated article, the polymer is extruded through a flat die onto a moving support. As the melt exits the die, the melt film is drawn down to the nip formed between the two rollers under the die, the pressure roll and the chill roll. A support moving at a higher speed than the melt film stretches the film to the required thickness. The film is pressed against the support by the pressure between the two rolls. Furthermore, the film is cooled and solidified by a low temperature chill roll. One of the unique parameters of the extrusion coating process, the drawdown ratio, is the ratio of the die gap to the thickness of the polymer film on the support.

  In a typical extrusion coating process, the support is fed at a high speed, typically greater than 100 m / min. Modern machines are designed to operate at line speeds up to 1000 m / min. In this application, “line speed” and “drawdown speed” are considered synonymous to indicate the speed of the support in the coating line.

  For example, Non-Patent Document 1 or Non-Patent Document 2 describes the extrusion coating process.

  Low density polyethylene (LDPE) is a resin mainly used for extrusion coating because of its ease of processing. However, the LDPE stiffness, barrier properties, temperature resistance and sealability, especially hot tack, are often unsatisfactory.

  Polypropylene is used in various products such as packaging films and molded products. Commercially available propylene polymers exhibit several desirable properties such as excellent heat resistance that makes polypropylene polymers preferred in many fields of application. High heat resistance is a desirable feature in many application areas such as food packaging and healthcare areas. When very high melting temperature polymers are required, propylene homopolymers are often the preferred choice. If a lower melting temperature or a wider temperature window is desired, a propylene-block copolymer is a preferred choice.

  Patent Document 1 discloses a film or sheet prepared by a typical film manufacturing process such as an inflation film method or a cast film method and used as a heat seal film. The film includes a polyolefin layer comprising a blend of a propylene-ethylene heterophasic polymer composition and an ethylene-based plastomer. The propylene-ethylene heterophasic polymer composition is a composition of propylene homo- or copolymer and ethylene-propylene copolymer, and uses two or more reactors (reactor blends) with a highly stereospecific Ziegler-Natta catalyst. ) By sequential polymerization. The film material of U.S. Pat. No. 6,053,077 is not disclosed for use in an extrusion coating process.

  Some examples of extrusion coating processes and extrusion coated articles are disclosed, for example, in US Pat.

  High line speeds set strict requirements on materials. Thus, while other optional properties, such as high heat resistance, may be desirable in many extrusion coating applications, a drawback to the use of polypropylene is that polypropylene exhibits poor processability in high speed extrusion coating. Signs of poor processability are instability of the web edge (edge weaving) and coating weight (pumping, draw resonance). Edge breaks or web breaks indicate the limit of drawdown speed. Instead, excellent processability means web stability at high drawdown speeds and drawdown ratios, and the coating weight is constant throughout the web.

  In order to make polypropylene more attractive in the extrusion coating process, the workability of the polypropylene in the extrusion coating process must be improved. One way to improve the processability of polypropylene is to modify the polymer composition by adding the processability enhancing component (s) to the polymer composition. Since LDPE is known to have excellent processability properties, it is known to improve the processability of propylene polymer compositions by adding LDPE to the composition. LDPE is also used to improve the polymer adhesion properties to the support layer.

  Furthermore, in addition to processability issues, polypropylene has a fairly narrow seal window, i.e., sealability is not ideal at all to produce extrusion coated articles where sealability is very important. Sealability is typically defined by measuring hot tack and heat seal temperature ranges defined later.

  In some cases, the seal strength is also taken into consideration. “Seal strength” is the strength of the heat seal after the seal is sufficiently cooled to ambient temperature.

  However, hot tack, i.e., the properties of the seal at the temperature after formation of the seal while the seal is still warm, is an important indicator of sealing performance in high speed packaging lines.

  There are several different hot tack properties that are important for heat sealable films. One important hot tack property is “starting temperature”. The onset temperature is the first temperature above ambient where a seal can be formed by applying a certain pressure to a certain thickness of film for a certain period of time. In general, a lower starting temperature is desirable. This is because less energy is required to use to form the seal and the time required to form the first seal at a certain sealing jaw temperature is reduced. Therefore, the production rate can be increased.

  Another important hot tack property is extreme hot tack or maximum hot tack, and the two terms have the same meaning in this application. Maximum hot tack is the maximum strength the seal has at a temperature above the starting temperature. Usually, maximum hot tack is desired to occur at the lowest possible temperature.

  In addition, an additional hot tack that is generally desired is a wide processing window where the film indicates that a suitable seal strength is measured over a wide temperature range.

  High temperature hot tack is also desirable where the seal strength is still sufficient at high temperatures.

  Hot tack is often determined by the composition utilized to form the film seal. As disclosed above, LDPE compositions widely used in the extrusion coating field have unsatisfactory hot tack properties for many applications. In some cases, the hot tack of LDPE-based extrusion coating compositions has been improved by blending the LDPE composition with a plastomer. However, such PE-plastomer compositions do not meet the requirements for high temperature resistance as disclosed above, and processability issues limit production capacity.

  Thus, because of the many advantageous properties of polypropylene compositions, polypropylene compositions are considered the basis for a suitable solution. However, problems with processability, particularly sealability such as hot tack and seal windows that are too narrow, must be solved.

  Propylene polymers, especially propylene homopolymers, have a narrow sealing window and the lowest sealing temperature is quite high. The sealing window and the minimum and maximum sealing temperatures depend not only on the heat-sealable layer but also on the layer to be sealed, such as the support layer. That is, the most desirable seal temperature, seal strength, and seal window should be defined each time, not absolute values. The seal window in the present application, when kraft paper is used as the support layer, is between the minimum seal temperature (SIT) at which the hot tack strength reaches 2N and the maximum seal temperature (SET) at which the hot tack strength remains at 2N. Is defined as the temperature range. Maximum hot tack strength is defined in this application as the maximum strength level along the 20 ° C. interval seal range.

  Therefore, it is strongly desired to provide a novel composition having high heat resistance and excellent sealability, particularly excellent hot tack. Furthermore, it is believed that additional benefits will be obtained if the seal window is wide, ie, the range between SIT and SET is wide. In addition, the processability of such layers should also be suitable for high speed lines.

  In addition, it would be particularly desirable to provide a polymer layer structure with excellent processability characteristics, high heat resistance and excellent sealability, particularly excellent hot tack. In addition, having a wider seal window, ie, a wider range between SIT and SET, would also be an additional advantage.

  It would also be highly desirable to provide an extrusion coated article such as a laminate comprising a support layer, at least one layer having high heat resistance, excellent sealability, and particularly excellent hot tack. In addition, a wider sealing window is an additional desirable beneficial feature as described above.

  Furthermore, it comprises a support layer and a polymer layer structure having the above-mentioned excellent sealing properties, excellent processability, adhesive properties, barrier properties and / or any other properties required for the defined end use It is also particularly desirable to have an article that is extrusion coated.

  One way to improve the processability properties of polypropylene, ie propylene homo- or copolymers, is to modify the polypropylene by adding low density polyethylene (LDPE) to the polypropylene polymer. However, adding LDPE does not contribute to achieving excellent hot tack properties.

International Publication No. 2011/039314 International Publication No. 2000/78859 International Publication No. 2013/124221

Crystalline Olefin Polymers, Part II, by R.C. A. V. Raff and K.M. W. Doak (Interscience Publishers, 1964), pages 478-484. Vieweg, Schley and Schwarz: Kunststoff Handbuch, Band IV, Polyfine, Carl Hanser Verlag (1969), 20, 412-420

  The present invention relates to a blend of a propylene polymer-based composition and an ethylene copolymer-based plastomer having excellent sealability, high heat resistance, and processability characteristics suitable for use in an extrusion coating process. The polymer composition comprising.

  Accordingly, a further object of the present invention is the use of a polymer composition comprising a blend of a propylene polymer-based composition and an ethylene copolymer-based plastomer in an extrusion coating process comprising the step of coating a support with said polymer composition.

  A further object of the present invention is to provide a polymer layer structure comprising a layer of polymer composition comprising a blend of a propylene polymer-based composition and an ethylene copolymer-based plastomer and a layer of any other polymer composition. The present invention further relates to an extrusion-coated article comprising at least one support layer and at least one layer of polymer composition comprising a blend of a propylene polymer-based composition and an ethylene copolymer-based plastomer. The article may further include additional layers.

  Furthermore, the present invention comprises at least one support layer and a polymer layer structure comprising a layer of polymer composition comprising a blend of propylene polymer-based composition and ethylene copolymer-based plastomer and a layer of any other polymer composition. Containing extrusion coated articles. The article may further include additional layers.

  The invention also relates to a process for producing an extrusion coated article.

The definition of the sealing property used for this invention is shown.

  At present, the inventors have found novel polymer compositions that meet the requirements of at least excellent sealability, high heat resistance and processability properties suitable for extrusion coating. In a preferred embodiment, a wider sealing window is also achieved.

  It has been found that certain blends of plastomer and propylene polymer-based compositions can be prepared and used as a polymer composition to improve sealability as measured by polymer hot tack. Furthermore, the composition meets the processability requirements of the extrusion coating process.

  Plastomers are generally defined as polymeric materials that combine the properties of elastomers and plastics, such as plastic processability and rubber-like properties. The important plastomer is selected from ethylene-alpha olefin copolymers.

Thus, the present invention
i)
(A-1) 55-95 wt% propylene polymer,
(A-2) 60-90 wt% propylene polymer composition (a) comprising a blend of 5-45 wt% low density ethylene polymer,
The amounts of (a-1) and (a-2) are based on the total weight of the composition (a), and the composition (a) has a melt flow rate of 10-50 g / 10 min (230 ° C./2.16 kg). A propylene polymer composition (a) having a MFR ₂ , and a Vicat softening temperature in the range of 120-155 ° C. measured according to ISO 306,
And ii) 10 to 40 wt% plastomer (b) of an ethylene copolymer with at least one α-olefin comonomer having 4 to 10 C atoms, provided that at least one comonomer is at least 6 Plastomer (b) which is a monomer having a C atom
A novel polymer composition (A) comprising a blend of
The amounts of (i) and (ii) relate to the novel polymer composition (A), wherein the plastomer (b) has a density of 880-912 kg / m ³ based on the total weight of the composition (A).

Furthermore, the present invention provides
1)
i)
(A-1) 55-95 wt% propylene polymer,
(A-2) 60-90 wt% propylene polymer composition (a) comprising a blend of 5-45 wt% low density ethylene polymer,
The amounts of (a-1) and (a-2) are based on the total weight of the composition (a), and the composition (a) has a melt flow rate of 10-50 g / 10 min (230 ° C./2.16 kg). A propylene polymer composition (a) having a MFR ₂ , and a Vicat softening temperature in the range of 120-155 ° C. measured according to ISO 306,
And ii) 10 to 40 wt% plastomer (b) of an ethylene copolymer with at least one α-olefin comonomer having 4 to 10 C atoms, provided that at least one comonomer is at least 6 Plastomer (b) which is a monomer having a C atom
A layer 1 of a polymer composition (A) comprising a blend of
the amount of i) and ii) is based on the total weight of the composition (A) and the plastomer b) has a density of 880-912 kg / m ³ , layer 1 of the polymer composition (A);
2) relates to a polymer layer structure (PL) comprising a composition (A) and a layer 2 of a different polymer composition.

  The polymer layer structure (PL) may comprise one or more layers 2.

Furthermore, the present invention provides
I. Support layer (S),
II. Heat-sealable polymer layer (H) of composition (A)
An extrusion coated article (EC) comprising:
The heat-sealable polymer layer (H) is
i)
(A-1) 55-95 wt% propylene polymer,
(A-2) 60-90 wt% propylene polymer composition (a) comprising a blend of 5-45 wt% low density ethylene polymer,
The amounts of (a-1) and (a-2) are based on the total weight of the composition (a), and the composition (a) has a melt flow rate of 10-50 g / 10 min (230 ° C./2.16 kg). A propylene polymer composition (a) having a MFR ₂ , and a Vicat softening temperature in the range of 120-155 ° C. measured according to ISO 306,
And ii) 10 to 40 wt% plastomer (b) of an ethylene copolymer with at least one α-olefin comonomer having 4 to 10 C atoms, provided that at least one comonomer is at least 6 Plastomer (b) which is a monomer having a C atom
Including
The amounts of (i) and (ii) relate to the extrusion coated article (EC), based on the total weight of the composition (A) and plastomer (b) having a density of 880-912 kg / m ³ .

The present invention further includes
I Support layer (S)
II Polymer layer structure (PL),
II-1)
i) (a-1) 55-95 wt% propylene polymer,
(A-2) 60-90 wt% propylene polymer composition (a) comprising a blend of 5-45 wt% low density ethylene polymer,
The amounts of (a-1) and (a-2) are based on the total weight of the composition (a), and the composition (a) has a melt flow rate of 10-50 g / 10 min (230 ° C./2.16 kg). A propylene polymer composition (a) having a Vicat softening temperature in the range of 120-155 ° C. measured according to MFR ₂ and ISO 306,
And ii) 10 to 40 wt% plastomer (b) of an ethylene copolymer with at least one α-olefin comonomer having 4 to 10 C atoms, provided that at least one comonomer is at least 6 Plastomer (b) which is a monomer having a C atom
Layer 1 of composition (A) comprising a blend of
Layer 1 of composition (A), wherein the amounts of (i) and (ii) are based on the total weight of composition (A), and plastomer (b) has a density of 880-912 kg / m ³ , and II- 2) Layer 2 of polymer composition different from composition (A)
Polymer layer structure (PL) containing
To an extrusion coated article (EC).

  The extrusion coated article may comprise two or more layers 2 in a polymer layer structure (PL).

  Layer 1 forms a heat-sealable layer and forms the surface layer of the extrusion coated article.

  Furthermore, the present invention is a process for producing an extrusion-coated article (EC) by an extrusion coating process, wherein the support (S) can be heat-sealed in a molten state through a flat die to the support. The heat-sealable polymer layer (H) comprises a composition (A) as defined above, or is coated by extruding layer (H) or at least co-extruding polymer layer structure (PL), or polymer layer structure ( PL) relates to a process as defined above. The heat-sealable layer (H) forms the surface layer of the article.

  In addition, the present invention also relates to the use of composition (A) as a heat-sealable layer in extrusion-coated articles.

  Additional details and preferred embodiments of the invention are disclosed in the specification and claims.

  The extrusion coated article may comprise at least one additional layer (M) in addition to the support layer (s) (S) and the heat-sealable polymer layer (H) or polymer layer structure (PL). Well, however, the heat sealable layer always forms the surface layer of the extrusion coated article. These optional layers (M) are any material suitable for use in extrusion coated articles, such as any polymer layer, metal foil, metallized polymer layer, fiber material, or combinations thereof. There may be. The layer (M) can be used for many purposes, typically as a polymeric material adhesive layer, tie layer, barrier layer or printed layer.

Thus, according to one preferred embodiment, the present invention provides:
1. Support layer (S)
2. 2. a layer comprising at least one heat-sealable polymer layer (H) made of composition (A) as defined above, itself or as part of a polymer layer structure (PL). Layer (M)
Including
However, the heat-sealable layer relates to the extrusion coated article, which is the outer layer of the extrusion coated article.

Support layer In the article of the present invention, the support layer comprises, inter alia, a fibrous support, such as paper, paperboard or kraft paper or woven or non-woven, plastic woven fabric, plastic film, such as stretched polypropylene film, PET film, PA film. Alternatively, it may include at least one layer of cellophane film or metal foil. In a preferred embodiment, the support layer is paper, paperboard or kraft paper, biaxially oriented polypropylene film, oriented PET film, oriented PA film, metallized biaxially oriented polypropylene film, plastic film that is woven or plastic, and aluminum foil. It is selected from a certain metal foil.

Propylene Polymer The propylene polymer used in the composition of the present invention may be a propylene homopolymer or a propylene copolymer with ethylene and / or an α-olefin comonomer of 4 to 12 C atoms. The propylene copolymer may be a random copolymer or a block copolymer. If very high heat resistance is desired, a propylene polymer having a high melting temperature may be selected. In that case propylene homopolymer is a preferred choice. If lower melting temperatures or wider temperature windows are desired, propylene-ethylene block copolymers are often the preferred choice.

  Propylene homopolymers and copolymers may be unimodal polymer compositions or multimodal polymer compositions.

  “Multimodal” or “multimodal distribution” describes a frequency distribution having several relative maximum values. In particular, the expression “polymer modality” refers to the shape of the molecular weight distribution (MWD) curve, ie the contour of the graph relating to the weight fraction of the polymer as a function of its molecular weight. If the polymer is produced in a continuous step process, i.e. utilizing reactors connected in series and using different conditions in each reactor, separate polymer fractions produced in different reactors. The minutes each have their own molecular weight distribution that can be quite different from each other. The resulting molecular weight distribution curve of the final polymer can be viewed by superimposing the molecular weight distribution curves of the polymer fractions, and accordingly has a clearer maximum value or at least features compared to the individual fraction curves. Spread. Polymers exhibiting such molecular weight distribution curves are called bimodal or multimodal, respectively.

  The expression homopolymer used in the present invention relates to a polypropylene consisting essentially of at least 97 wt%, preferably at least 99 wt%, most preferably at least 99.5 wt%, in particular 99.8 wt% of propylene units. In a preferred embodiment, only propylene units are detectable in the propylene homopolymer.

Polypropylene according to the invention is a propylene random copolymer comprising monomers copolymerizable with propylene, such as ethylene and / or comonomers such as C _{4 to} C ₁₂ α-olefins, in particular ethylene and / or C _{4 to} C ₁₀ α-olefins In some cases, the C _{4 to} C ₁₀ α-olefin is preferably 1-butene and / or 1-hexene. Preferably the random propylene copolymer comprises a monomer selected from the group consisting of ethylene, 1-butene and 1-hexene. Preferably, the total amount of comonomer, more preferably ethylene, in the propylene copolymer is preferably greater than 0.5 mol% but less than 10.0 mol%, and even more preferably greater than 0.5 mol% but less than 7.0 mol%.

  The polypropylene can also be a propylene copolymer comprising a polypropylene matrix and an ethylene-propylene rubber (EPR).

  The polypropylene matrix may be a homopolymer or a copolymer, more preferably a multimodal homopolymer such as bimodal or a multimodal copolymer such as bimodal. When the polypropylene matrix is a propylene copolymer, the comonomer is preferably ethylene or butene. However, other comonomers known in the art are also suitable. The preferred amount of comonomer in the polypropylene matrix is at most 8.00 mol%. If the propylene copolymer matrix has ethylene as a comonomer component, it is particularly preferred that the amount of ethylene in the matrix is at most 8.00 mol%, more preferably less than 6.00 mol%. When the propylene copolymer matrix has butene as the comonomer component, it is particularly preferred that the amount of butene in the matrix is at most 6.00 mol%, more preferably less than 4.00 mol%.

  Preferably, the ethylene-propylene rubber (EPR) in the total propylene copolymer consists of up to 60 wt%. More preferably, the amount of ethylene-propylene rubber (EPR) in the total propylene copolymer is in the range of 15-60 wt%, even more preferably in the range of 20-50 wt%.

  Furthermore, when the polypropylene is a copolymer comprising a polypropylene matrix and ethylene-propylene rubber (EPR), the ethylene-propylene rubber (EPR) preferably has an ethylene content of up to 65 wt%.

  In one embodiment, the polypropylene is a branched polypropylene. Branching can be achieved by using a specific catalyst, ie a specific single site catalyst. See, for example, EP 1 892 264, which is described in more detail for the preparation of branched polypropylene by use of a metallocene catalyst. Typically such branched polypropylenes have a branching index in the range of 0.3 to 0.9, such as less than 1.0, more preferably less than 0.9, and even more preferably in the range of 0.4 to 0.8. g ′. The branched polypropylene may be a branched polypropylene homopolymer or a branched propylene copolymer.

In another preferred embodiment, the branched polypropylene (b-PP) is so-called high melt strength polypropylene (HMS-PP). Unlike the branched polypropylene discussed in the previous paragraph, high melt tension polypropylene (HMS-PP) has been obtained by chemical modification as discussed in detail below. It is known that such polymers can be determined by their rheological behavior. Accordingly, branched polypropylene, particularly high melt tension polypropylene (HMS-PP), preferably measured at a strain rate of 3.0 s ⁻¹ is at least 1.7, more preferably at least 1.9, even more preferably 1. It has a strain hardening factor (SHF) in the range of 7 to 7.0, and even more preferably in the range of 1.9 to 6.5, and a Henky strain of 2.5. Additionally or alternatively, high melt tension polypropylene (HMS-PP) can be defined by the branching index g ′. Accordingly, high melt tension polypropylene (HMS-PP) is less than 1.0, more preferably less than 0.9, even more preferably 0.3 to 0.9, such as in the range of 0.4 to 0.8. It is preferable to have a branching index g ′ in the range of

  Furthermore, the polypropylene used in the present invention may be a nucleated polymer or a filled polymer, but the filler material is preferably an inorganic filler.

Ethylene Polymer The ethylene polymer used in the composition of the present invention is a low density ethylene polymer (LDPE).

  The meaning of low density polyethylene (LDPE) is well known and reported in the literature. The term LDPE is an abbreviation for low density polyethylene, but this term is not intended to limit the density range, but to cover HP (high pressure) polyethylene having low, medium and higher density. Is done. In the HP ethylene polymerization process, autoclaves and tubular reactors are typically used. The term LDPE describes and distinguishes only the properties of HP polyethylene that have typical characteristics, such as a different branched structure compared to polyethylene produced in the presence of an olefin polymerization catalyst. Further, the low density polyethylene (LDPE) may be unsaturated. Preferably, the low density polyethylene (LDPE) used in the present invention is an ethylene homopolymer.

  When the low density polyethylene (LDPE) is a copolymer, the low density polyethylene (LDPE) is typically, but not limited to, a comonomer selected from acrylate, acrylic acid, methacrylate, methacrylic acid and acetate including.

Typically and preferably the density of low density polyethylene (LDPE) is higher than 860 kg / m ³ . Preferably a low density polyethylene (LDPE), i.e. the density of the LDPE homopolymer or copolymer is not higher than 940 kg / ^{m 3,} i.e. in the range of 860~940kg / ^{m 3,} preferably 880~930kg / ^{m 3,} more preferably It is 900-930 kg / m ³ like 910-925 kg / m ³ . The LPPE used in the present invention is preferably an ethylene homopolymer having a density in the range of 860-940 kg / m ³ , preferably 880-930 kg / m ³ , more preferably 900-930 kg / m ³ . A particularly preferred density is 910 to 925 kg / m ³ .

  The components of propylene composition (a), namely propylene polymer (a-1) and low density polyethylene (a-2) are thus prepared separately in different polymerization processes to form propylene polymer composition (a). Combined by blending.

  “Blend” or “blending” in this application means that different components are combined by mechanical blending such as melt or dry blending. The components are prepared separately in different processes.

  The phrase “polymer reactor blend” refers to a blend that is a polymer blend prepared in a multi-stage polymerization process. Thus, the blends of the present invention are not optional reactor blends.

Plastomer The plastomer used in the present invention is a low density ethylene-copolymer comprising an ethylene polymer with at least one olefin comonomer. The comonomer is an α-olefin comonomer with 4 to 10 C atoms, provided that at least one comonomer is a monomer having at least 6 C atoms. That is, when the plastomer is an ethylene terpolymer, at least one monomer has 6 or more C atoms. Preferably, the comonomer in the ethylene-copolymer is selected from α-olefins of 6 to 10 C atoms, preferably 6 to 8 C atoms, more preferably one α of 6 to 8 C atoms. -Copolymers of ethylene with olefins, in particular ethylene-octene copolymers.

The plastomers used in the present invention typically have a low density in the range of 880-912 kg / m ³ , preferably 885-910 kg / m ³ , and in some embodiments 890-905 kg / m ³ . The plastomer MFR ₂ (190 ° C./2.16 kg) is in the range of 3-25 g / 10 min, preferably in the range of 5-20 g / 10 min, and in some embodiments in the range of 5-15 g / 10 min. The plastomer used in the present invention is preferably produced in a solution process in the presence of a metallocene catalyst.

Optional additional layer (M)
Layer (M) may be any other material suitable for use in extrusion coated articles, such as any other polymer layer, metal foil, fiber material, or combinations thereof. Layer M can be, for example, paper, paperboard or kraft paper or woven or non-woven, plastic film such as biaxially oriented polypropylene film, oriented polypropylene film such as metallized biaxially oriented polypropylene film, optionally stretched PET film, optional It may include a metal film which is a PA film or a cellophane film or an aluminum foil which has been stretched. The composition may be optionally modified with other ingredients to obtain the desired properties. The additional layer M made of the polymer composition may also form at least one layer 2 of a polymer layer structure (PL).

A preferred composition (A) of the present invention comprises i) 65-85 wt%, preferably 70-85 wt%, and even more preferably 75-85 wt% of composition (a), and the total amount of composition (A), and ii) 15-35 wt%, preferably 15-30, and even more preferably 15-25 wt% plastomer (b)
Contains a blend of

Furthermore, the preferred composition (a) comprises (a-1) 60-95 wt%, more preferably 65-90 wt% propylene polymer and (a-2) 5-40 wt%, based on the total weight of the composition (a). %, More preferably 10-35 wt% of a blend of low density ethylene polymers.

  According to the above definition, components (a-1) and (a-2) are prepared in separate and distinct polymerization processes and combined by blending.

Composition (a) has a melt flow rate MFR ₂ of 10-50 g / 10 min (230 ° C./2.16 kg), and the Vicat softening temperature of composition (a) is 120-155 ° C. measured according to ISO 306. In the range of 125 to 155 ° C.

Thus, one preferred composition (A) is
i)
A blend of (a-1) 55-95 wt% propylene polymer, more preferably 65-90 wt% propylene polymer and (a-2) 5-45 wt%, more preferably 10-35 wt% low density ethylene polymer. 70-85 wt% of composition (a),
The amounts of (a-1) and (a-2) are based on the total weight of the composition (a), and the composition (a) has a melt flow rate of 10-50 g / 10 min (230 ° C./2.16 kg). A composition (a) having a Vicat softening temperature measured according to MFR ₂ and ISO 306 in the range of 125-155 ° C;
ii) 15-30 wt% plastomer (b) of an ethylene copolymer with at least one α-olefin comonomer of 6-10 C atoms;
A blend of
The amounts of (i) and (ii) are based on the total weight of composition (A) and plastomer (b) has a density of 880-912 kg / m ³ and MFR ₂ (190 ° C. / 2.16 kg), including the blend.

  Preferably, the plastomer (b) used in all embodiments of the present invention is produced in a solution process in the presence of a metallocene catalyst.

The plastomer used in all embodiments of the invention has an MFR ₂ (190 ° C./2.16 kg) in the range of 3-25 g / 10 min, preferably 5-20 g / 10 min.

Furthermore, the plastomer used in all embodiments of the present invention has a density in the range of 880-912 kg / m ³ , preferably 885-910 kg / m ³ .

In one preferred embodiment, the plastomer has an MFR ₂ (190 ° C./2.16 kg) in the range of 5-20 kg 10 / min, and a density in the range of 885-910 kg / m ³ .

The MFR ₂ (230 ° C./2.16 kg) of the composition (a) may be in the range of 10-50 g / 10 min, preferably 12-50 g / 10 min.

In one preferred embodiment - Propylene polymer (a-1) is a propylene homopolymer or propylene ethylene block copolymers, and / or - a low density ethylene polymer (a-2) has a density of 900~930kg / ^{m 3.}

  All preferred embodiments of composition (A), (a) and plastomer (b) and layers (S), (H), (PL), layer 1, layer 2 and (M) are present as preferred embodiments. Applicable to all extrusion coated articles (EC) of the invention.

  The compositions (a) and (A) of the present invention may be formed by any common blending technique such as the use of melt or dry blending. When using melt blending techniques to form composition (A), the polymer components are melt compounded in a compounding extruder, typically a twin screw extruder. It is also possible to use a dry blend of the components in the extrusion coating line. Optionally, additional additives such as fillers, slip agents, anti-blocking agents, antioxidants, chill roll release agents and polymer processing aids may be incorporated into the melt and dry blends.

  The composition (A) of the present invention is surprisingly well suited for the formation of heat sealable films with improved hot tack and use in extrusion coated articles. By using a film made of the composition (A) as the only layer on the support or as the outer layer of an extrusion coated multilayer article, the extrusion coated article has excellent hot tack properties such as Excellent sealing properties are very suitable for packaging materials that are required within a wide temperature range.

  Using the composition (A) as the only layer on the support or part of the polymer layer structure (PL) as defined above, very good processability is obtained in addition to excellent sealing properties. As defined above, said polymer layer structure (PL) comprises a layer of composition (A) (layer 1) and another layer of polymer composition different from composition (A) (layer 2). In order to meet the excellent processability properties, layer 2 should also be a polymer composition that satisfies the excellent processability properties. Examples of such polymer compositions suitable for layer 2 include LDPE optionally blended with polypropylene (most of the polymer is LDPE), most of the polymer is polypropylene, polypropylene blend with LDPE, or processability And any other polymer composition that meets the requirements of other properties required for each application. Where excellent heat resistance is important, a polypropylene blend with LDPE is a reasonable choice, where the majority of the polymer is polypropylene. One possibility is to use as the layer 2 a polypropylene composition containing 5-45 wt% LDPE, ie the composition (a) defined above. This type of polymer layer structure also provides excellent processability properties and excellent adhesion to the support layer (S) in addition to very good sealing properties in extrusion coating processes, even in high speed processes.

  As described above, heat sealability is one of the main indicators used for evaluation of packaging materials. The heat seal characteristics include hot tack strength and heat seal temperature range. Hot tack strength refers to the peel force when the seal area is not yet completely cooled.

  The composition (A) of the present invention used as a heat seal layer (H) of an extrusion coated article, in which kraft paper is used as a support, has a maximum hot tack strength of more than 4N, preferably at least 4.5N. Have Maximum hot tack strength is defined as the maximum strength level along the seal range at 20 ° C. intervals.

  Other important features of the seal material include SIT value and SET value. The minimum sealing temperature (SIT) of the present invention is defined as the temperature at which the hot tack strength reaches 2N when kraft paper is used as the support layer, and the maximum sealing temperature (SET) remains at the hot tack strength of 2N. Temperature.

  The definition of sealability used in the present invention is illustrated in FIG. It should be noted that the values disclosed in FIG. 1 are merely examples for clarifying definitions and do not represent the characteristics of the present invention.

  Low SIT values and wide seal windows are particularly important seals in the packaging industry where line speed and process integrity are essential elements.

  The extrusion coating process may be performed using conventional extrusion coating techniques. Thus, at least the composition (A) according to the invention is typically sent to the extruder in the form of pellets optionally containing additives. The polymer melt reaches the support to be coated from the extruder, preferably through a flat die. The coated support is cooled on a chill roll and then sent to an edge trimmer and wound up. The die width typically depends on the size of the extruder used. Therefore, in the case of a 90 mm extruder, the width is preferably 600 to 1,200 mm, in the case of a 115 mm extruder, 900 to 2,500 mm, in the case of a 150 mm extruder, 1,000 to 4,000 mm and a 200 mm extruder. In the case, the range of 3,000 to 5,000 mm may be used. The line speed (drawdown speed) is preferably 75 m / min or more, more preferably at least 100 m / min. For most machines in commercial operation, the line speed is preferably above 300 m / min or above 500 m / min. Modern machines are designed to operate at line speeds up to 1,000 m / min, for example 300-800 m / min. The temperature of the polymer melt is typically 240-330 ° C. The polypropylene composition (A) of the present invention may be extruded as a single layer coating or an outer layer on a support in a coextrusion process. In multilayer extrusion coating, the polymer layer structure defined above and optionally other polymer layers may be coextruded. Further, if desired or necessary, ozone and / or corona treatment can be performed in a known manner.

  The main end use of extrusion coated products and articles obtained by use of the heat-sealable composition (A) according to the invention is for liquid packaging, snacks, confectionery, meat for milk, juice, wine or other liquids Flexible packaging for cheese and pharmaceuticals, detergent cartons, rigid packaging such as oven or microwave cups and plates, or packaging applications such as sterilizable food packaging, as well as photographic paper or paper reels and Also in industrial applications such as ream packaging and preferably industrial laminates with sterilizable and / or retortable properties.

  Accordingly, the present invention also provides, as outlined above, a support, each article having at least one layer of excellent sealing properties which is a propylene polymer-based composition (A) according to the present invention on at least one surface. provide.

  Moreover, the present invention is further directed to the use of the articles of the invention as packaging and lid materials, in particular as packaging and lid materials for food and / or pharmaceutical products.

  In some embodiments of the present invention, the extrusion coated article is subjected to various machining and molding operations in downstream processes. Such operations include, for example, drilling, punching and bending.

  The polymer layer of the extrusion coated support preferably has a thickness in the range of 5 to 1,000 μm, more preferably 5 to 100 μm, for example in the range of about 7 to 50 μm. The specific thickness is selected depending on the nature of the support, its expected handling conditions, and most importantly, the subsequent use of the final product. The thickness of the support can generally be chosen freely and does not affect the coating process. The thickness of the support is typically 1 to 10,000 μm, for example 10 to 600 μm.

  The temperature of the polymer melt, i.e. the composition melt, is typically 240-330C, preferably 250-315C.

  It is also possible to utilize a coating line with at least two extruders in order to be able to produce multilayer coatings with different polymers.

Thus, according to one embodiment of the present invention, the extrusion coated article (EC) is a heat-sealable layer (H) in a molten state through a flat die through the support at a temperature of 240-320 ° C. Or at least coextruding the polymer layer structure (PL) to extrusion coat the support (S) at a drawdown speed of at least 150 m / min, wherein the heat sealable polymer layer (H) May be produced by a step comprising the composition (A) as defined above or being part of the polymer layer structure (PL) as defined above.

  Furthermore, it is possible to arrange for the polymer melt coming out of the die to improve adhesion, for example by ozone treatment, and / or the handling of the support by corona treatment or flame treatment. In the corona treatment, for example, a support is passed between two conductor elements functioning as electrodes, and a high voltage, usually an alternating voltage (approximately 10000 V and 10,000 Hz) is applied between the electrodes so that spray discharge or corona discharge can occur. The By spray discharge or corona discharge, air on the support surface is ionized and reacts with molecules on the support surface.

  Extrusion-coated articles comprising the composition of the invention and their preparation are described in more detail by the following examples. Unless otherwise stated, all parts and ratios are on a weight basis.

  The following definitions of terms and determination methods apply to the following examples in addition to the above general description of the invention, unless otherwise defined.

Measuring method:
Hot tack force Determine and report the maximum hot tack force, ie the maximum value of the force / temperature diagram.

Hot tack measurement was performed using a J & B hot tack tester according to ASTM F 1921 method. This standard requires the sample to be cut into 15 mm wide sections. Samples are introduced into the hot tack tester vertically with both ends attached to mechanical locks. Next, it is sealed with a tester, the hot seal is peeled off, and the resistance is measured.
Seal pressure, 1.5 N / mm ²
Sealing time, 0.5s
Cooling time, 0.2s
Peeling speed, 200mm / s

  The hot tack of each sample was determined by testing the hot tack force at a temperature ranging from 90 ° C. to a temperature where the hot tack force measured was less than 1N. This standard requires that at least three parallel measurements be made. The temperature was increased in increments of 5 ° C.

SIT and SET
SIT and SET values are obtained from hot tack measurements. In the present invention, the minimum seal temperature (SIT) is defined as the temperature (° C.) at which the hot tack strength reaches 2N, and the maximum seal temperature (SET) is the temperature (° C.) at which the hot tack strength remains at 2N.

Maximum Hot Tack Strength Maximum hot tack strength is defined as the highest strength (N) level over a 20 ° C. seal range.

  Vicat is measured according to ISO 306.

  The density is measured according to ISO 1183.

Melt flow rate MFR ₂
The melt flow rate MFR ₂ of polyethylene, such as low density ethylene polymer, is measured according to ISO 1133 at 190 ° C. and a load of 2.16 kg unless otherwise noted. The melt flow rate MFR ₂ of the polypropylene polymer is measured according to ISO 1133 at 230 ° C. and a load of 2.16 kg unless otherwise noted.

Layer material for extrusion coated articles Support layer As support layer (S), UG kraft paper having a basis weight of 70 g / m ² in all examples was used.

Polymers and compositions Polymer compositions (a)
The polymer composition (a) was formed by melt blending a propylene homopolymer with homo LDPE. The amount of LDPE ranges from 5 to 45 wt% to obtain MFR ₂ (230 ° C / 2.16 kg load) of composition (a) in the range of 20-30 g / 10 min, and Vicat temperature in the range of 125-130 ° C. Adjusted.

  The same composition (a) was used in all examples as the polymer layer 2 between the support (craft paper) layer (S) and the heat-sealable polymer layer (H).

Plastomer (b)
As the plastomer, an ethylene-octene copolymer produced by a solution process using a metallocene catalyst and having a density of 902 kg / m ³ and MFR ₂ (190 ° C./2.16 kg) of 10 g / 10 min was used.

Polymer composition (A)
Composition (A) was formed by dry blending composition (a) defined above with ethylene-octene plastomer (b) as defined above. The amount of plastomer (b) was 20 wt% with respect to the total amount of composition (A). This composition was used as layer 1 of IE1.

Other polymer compositions As other polymer compositions, propylene random copolymer compositions having an MFR _{2 of} 8 g / 10 min and an ethylene content of 2 wt% (C2) or 4 wt% (C4) were used. These compositions are used for Comparative Examples CE2 and CE3.

In all examples, the polymer layer of composition (a) was used as a layer between the support layer and the heat-sealable layer (H). Thus, the extrusion coated article prepared in this example can be defined as comprising a support layer (S) and a polymer layer structure (PL) as follows:
-Polymer layer structure (PL)
Layer 1 (= top layer = heat sealable layer (H), as defined in each example)
Layer 2 (= same in invention example and comparative example = composition a)
- the support layer (S) = UG kraft paper, 70 g ^{/ m} 2 in all examples.

The total amount of polymer composition in the polymer layer structure was 18 g / m ² (9 g / m ² in layer 1 and 9 g / m ^{2 in} layer ² ).

Invention Example 1 (IE1)
The polymer composition (A) was used as the top layer (layer 1), ie the heat-sealable layer (H), in the extrusion coated article of the present invention.

Thus, the polymer layer structure of IE1 is:
Layer 1 Polymer composition (A)
Layer 2 Polymer composition (a)

Comparative Example 1 (CE1)
Composition a) was used as the top layer (H) (layer 1). No plastomer was added to the composition.

Thus, the polymer layer structure of CE1 is:
Layer 1 Polymer composition (a)
Layer 2 Polymer composition (a)

Comparative Example 2 (CE2)
As the top layer (H) (layer 1), a propylene random copolymer composition (composition (C2)) having an MFR _{2 of} 8 g / 10 min and an ethylene content of 2 wt% was used. No plastomer was added to the composition.

Thus, the polymer layer structure of CE2 is:
Layer 1 Polymer composition (C2)
Layer 2 Polymer composition (a)

Comparative Example 3 (CE3)
As the top layer (H) (layer 1), a propylene random copolymer composition (composition (C4)) having an MFR _{2 of} 8 g / 10 min and an ethylene content of 4 wt% was used. No plastomer was added to the composition.

Thus, the polymer layer structure of CE3 is:
Layer 1 Polymer composition (C4)
Layer 2 Polymer composition (a)

Formation of extrusion coated article (EC):
The extrusion coated article consisted of the same support layer (S) and polymer layer structure as shown in IE1 and CE1-CE3. Articles were prepared according to the following method.

  The extrusion coating operation was performed on a Beloit coextrusion coating line. The line was equipped with a Peter Cloeren EBR die and a five-layer feedblock. The line width was 850 to 1,000 mm and the maximum possible line speed was 1,000 m / min. The line speed was maintained at 150 m / min.

  In an EBR die (EBR stands for “edge bead reduction”), the two deckles, the upper and lower deckles are adjusted to minimize edge beading. Deckling is indicated as the position of the deckle in mm from the starting opening position. The first number indicates the position of the upper deckle, and the second number indicates the position of the lower deckle. For example, Dickeling 70/30 means that the upper deckle is moved 70 mm from the edge of the die and the lower deckle is moved 30 mm from the edge of the die.

In the above coating line, UG kraft paper was coated with a coextruded structure consisting of a heat-sealable top layer H (layer 1) and layer 2 of composition a) bonded to a paper support as disclosed above. . (The temperature of the polymer melt was set at 290 ° C., and the temperature profile of the extruder was 200-240-290-290 ° C. The chill roll was matted and the surface temperature was 15 ° C. Used. The die opening was 0.65 mm and the nip spacing was 160 mm The melt film first touched the support at +10 mm from the nip to the support side The pressure on the pressure roll was 3.0 kp / cm ² . The line speed was 150 m / min.

For all samples, melt ozonation (Wedeco) and support corona treatment (Vetaphone) were utilized. The set value of ozone was 2.0 kW, so the concentration of ozone was 25 g / m ³ . The applicator distance and angle from the molten film were 70 mm and 45 ° C. The Betaphone ET5 corona processor had an output power of 12 kW and a frequency of 18-35 kHz. The Betaphone ET5 corona processor was equipped with an HF amplifier with an output voltage of 15-25 kV and a multi-profile aluminum electrode. The set value of the corona used was 12.0 kW.

  The sealing properties of the extrusion coated articles of Invention Example IE1 and Comparative Examples CE1-CE3 are disclosed in Table 1.

As can be seen from the examples, the inventive examples show an increase in maximum hot tack strength and minimum SIT compared to a composition without plastomer. SET was still maintained at a high level. Thus, the use of the composition of the present invention widens the seal window.

Claims (17)

i)
(A-1) 55-95 wt% propylene polymer,
(A-2) 5-45 wt% low density ethylene polymer (LDPE) which is high pressure polyethylene
60-90 wt% propylene polymer composition (a) comprising a blend of:
The amounts of (a-1) and (a-2) are based on the total weight of the composition (a), and the composition (a) has a melt flow rate of 10-50 g / 10 min (230 ° C./2.16 kg). A propylene polymer composition (a) having a MFR ₂ , and a Vicat softening temperature in the range of 120-155 ° C. measured according to ISO 306,
And ii) 10 to 40 wt% plastomer (b) of an ethylene copolymer with at least one α-olefin comonomer having 4 to 10 C atoms, provided that at least one comonomer is at least 6 Plastomer (b) which is a monomer having a C atom
A polymer composition (A) comprising a blend of
The polymer composition (A), wherein the amounts of (i) and (ii) are based on the total weight of the composition (A), and the plastomer (b) has a density of 880-912 kg / m ³ . It said plastomer (b) is an ethylene -C6~C10α- olefin copolymers chromatography, the polymer composition according to claim 1 (A).   The polymer composition (A) according to claim 1 or 2, wherein the plastomer (b) is produced by a solution process in the presence of a metallocene catalyst. It said plastomer (b) is 3~25g / 10mi n has a MFR ₂ (190 ℃ / 2.16kg) of polymeric composition according to any one of claims 1 to 3 (A). The polymer composition is based on the total amount of composition (A) i) 70-85 wt% propylene composition (a) and ii) 15-30 wt% plastomer (b)
The polymer composition (A) according to any one of claims 1 to 4, comprising a blend of The propylene polymer composition (a) (a-1) is a propylene random or block copolymers over the propylene homopolymer or an ethylene and / or of 4 to 12 C atoms α- olefin comonomer, claim 1. The polymer composition (A) according to 1. The low density ethylene polymer (a-2) is have a density of 860~940kg / ^{m 3,} the polymer composition according to any one of claims 1 to 6 (A). 1)
i)
(A-1) 55-95 wt% propylene polymer,
(A-2) 5-45 wt% low density ethylene polymer (LDPE) which is high pressure polyethylene
60-90 wt% propylene polymer composition (a) comprising a blend of:
The amounts of (a-1) and (a-2) are based on the total weight of the composition (a), and the composition (a) has a melt flow rate of 10-50 g / 10 min (230 ° C./2.16 kg). A propylene polymer composition (a) having a MFR ₂ , and a Vicat softening temperature in the range of 120-155 ° C. measured according to ISO 306,
And ii) 10 to 40 weight percent of a plastomer (b) of an ethylene copolymer with at least one α-olefin comonomer having 4 to 10 C atoms, provided that at least 6 comonomer is at least 6 A plastomer (b) which is a monomer having a C atom of
A layer 1 of a polymer composition (A) comprising a blend of
The amount of (i) and (ii) is based on the total weight of the composition (A), and the plastomer (b) has a density of 880-912 kg / m ³ and a layer 1 of polymer composition (A) ,
2) A polymer layer structure (PL) comprising the composition (A) and a layer 2 of a polymer composition different from the composition (A). I. Support layer (S),
II. Heat-sealable polymer layer (H)
An extrusion coated article (EC) comprising:
The heat-sealable polymer layer (H) is
i)
(A-1) 55-95 weight percent propylene polymer;
(A-2) 5-45 weight percent low density ethylene polymer (LDPE) which is high pressure polyethylene
60-90 weight percent propylene polymer composition (a) comprising a blend of:
The amounts of (a-1) and (a-2) are based on the total weight of the composition (a), and the composition (a) has a melt flow rate of 10-50 g / 10 min (230 ° C./2.16 kg). MFR ₂ , and Vicat softening temperature in the range of 120-155 ° C. measured according to ISO 306, propylene polymer composition (a),
And ii) 10 to 40 weight percent of a plastomer (b) of an ethylene copolymer with at least one α-olefin comonomer having 4 to 10 C atoms, provided that at least 6 comonomer is at least 6 A plastomer (b) which is a monomer having a C atom of
A composition (A) comprising a blend of
Extruded coated articles (EC), wherein the amounts of (i) and (ii) are based on the total weight of the composition (A) and the plastomer (b) has a density of 880-912 kg / m ³ .   The article comprises a layer 2 of a polymer composition different from the composition (A), located between the support layer (S) and the heat-sealable polymer layer (H). Extruded coated article (EC) as described in 1. Ii support layer (S)
II-i Polymer layer structure (PL) as defined in claim 8
Only including,
The extrusion coated article (EC) according to claim 9, wherein in the polymer layer structure (PL), the layer 1 forms a heat sealable polymer layer (H ).   The extrusion-coated article (EC) according to any one of claims 9 to 11, wherein the plastomer (b) is produced in a solution process in the presence of a metallocene catalyst. It said plastomer b) is an ethylene -C6~C10α- olefin copolymers chromatography, was extrusion coated as described in any one of claims 9 to 12 articles (EC).   14. The support layer (S) is selected from the group of paper, paperboard, kraft paper, plastic film, metallized plastic film, metal foil, woven fabric or plastic or combinations thereof. Extruded coated article (EC) as described in 1.   15. Extruded coated according to any one of claims 9 to 14, wherein the article comprises at least one layer (M) of a polymer film, a metal foil, a metallized polymer film, a layer of fiber material or a combination thereof. Article (EC). Extrude the support (S) at a drawdown speed of at least 150 m / min and extrude the molten heat-sealable layer (H) through a flat die onto the support at a temperature of 240 to 320 ° C., or at least a polymer layer structure ( PL) coextruding to include extrusion coating,
The heat-sealable polymer layer (H) is extrusion coated, comprising the composition (A) as defined in claim 1 or being part of the polymer layer structure (PL) as defined in claim 8. Process for manufacturing a finished article (EC).   Use of the polymer composition (A) as defined in claim 1 as a heat-sealable layer in an extrusion-coated article.